The research described in this competing renewal proposal seeks through five aims to maintain and enhance the Americans' Changing Lives (ACL) study, which was started in 1986, and is the oldest on-going nationally- representative prospective study of a broad range of socioeconomic and psychosocial determinants of health, and of how health and health disparities play out over the full life course. It is a unique research project and major public use data set for analyzing and understanding social disparities in the way health changes with age, especially the postponement or compression of mortality, morbidity, functional limitations, and disability over the entire adult life course. The ACL study focuses on and contributes to the two overarching goals of the U.S. Public Health Service's Healthy People 2010 strategic plan: 1) increasing healthy active life expectancy and 2) reducing social disparities in health. The five specific aims of this proposal are: 1) to extend the longitudinal follow-up of surviving members of the 1986 ACL sample by conducting a fifth wave of data collection and continuing annual mortality ascertainment using the National Death Index, death certificate verification, and other mortality tracking processes through at least 2013; 2) to develop a methodological/biostatistical core for ACL which will a) provide expertise to the project for increasingly complex analyses of the determinants of long term changes and trajectories in health, and b) develop and apply innovative statistical/methodological research to improve longitudinal analysis and adjust for selection and attrition in analyses, thus, improving our and others' ability to utilize ACL and similar longitudinal data; 3) to understand mechanisms underlying social disparities in morbidity and mortality and the compression thereof; 4) to add new measures regarding medical care, disability and impairment to ACL Wave 5 so as to expand the health status outcomes under study and investigate the role of selected biomedical interventions in maintaining, enhancing or alleviating social disparities in the way different health outcomes change with age; and 5) to capitalize on existing measures of work conditions and transitions and add new ones to ACL5 in order to investigate changing patterns and sequencing of paid work, unpaid productive activities, and retirement, in the context of current crises of the American and world economies.